Google, Apple and now Microsoft have felt pressure from Beijing amid tensions
over access to markets and spying

Microsoft offices in China were raided on Monday by government officials investigating monopoly concerns, further undermining the confidence of American technology companies chasing growth in the world's second-largest economy.

The company said it was "happy to answer the government's questions" in response to the surprise visit, but it has again demonstrated some of the sensitivities for powerful foreign companies as China aims to build its own technology industry.

In facing such pressure, Microsoft has joined a club that includes Apple, Google and the mobile microchip giant Qualcomm.

A pattern has emerged. American technology companies who find themselves criticised in the state-controlled Chinese media can take it as a warning.

Last year Apple's chief executive, Tim Cook, was forced to publicly apologise to Chinese consumers following a run of stories in newspapers and on television lambasting the way it treated them.

Not normally known for its contrition, Apple bowed to the pressure in the knowledge that the distribution deal it was seeking with China Mobile, the world's largest mobile network operator, was worth the temporary ignominy.

Since then, however, relations between Washington and Beijing have been strained by the former NSA contractor Edward Snowden, and Chinese media and regulatory pressure on US technology firms, accused of collaborating with spies, has escalated.

Apple this month issued an unusual statement in response to claims that the iPhone could be used to track Chinese users' locations and leak state secrets, for instance. Microsoft got similar treatment over Windows 8.1 last month, with a widely reported ban of the operating system on government computers.

To what degree China's clampdown on American technology is motivated by heightened espionage concerns - or conveniently excused by them - is open to debate. Beijing is also keen to foster the country's own technology sector, as witnessed by vast new high-tech developments in cities such as Wuhan.

Qualcomm, which invested many of the technologies behind 3G and 4G networks, is under investigation as a monopolist.

President Xi Jinping has meanwhile made reducing reliance of foreign technology a priority.

"Only if core technologies are in our own hands can we truly hold the initiative in competition and development," he said last month.

"Only then can we fundamentally ensure our national economic security, defence security and other aspects of security."

So there is probably an element of protectionism to the latest troubles for US technology companies in China. It cuts both ways, however. Huawei, the Chinese telecoms equipment vendor, has been subject to claims it is a security threat in the US and been frozen out of the market.

Ironically, when Windows was at its most dominant in the last decade, Microsoft virtually ignored China because of endemic software piracy. The company has now recognised its importance as a market for online services, but the raid on it is another sign that the environment for big Western companies in China has changed for the worse.